Hepatocellular carcinoma (HCC) is one of the most common diagnosed malignancies and one of the most frequent causes of cancer related deaths worldwide. Incidence is particularly high in Asia and Sub-Saharan Africa due to the large incidence of hepatitis B and C, both of which are complicated by hepatic cirrhosis, the greatest risk factor for HCC. Increasing trends in HCC have been reported in Western countries. Further, the liver is one of the most common sites of metastatic cancer arising in other organs.
When feasible, surgical resection or liver transplant is the accepted standard therapeutic approach, and has the highest success rate of available treatment methods for primary and metastatic liver cancer. Unfortunately, only approximately 15% of patients are candidates the surgery. Patients who do not qualify for surgery are offered other therapeutic solutions such as for example chemotherapy and radiotherapy, however these other solutions have variable success rates.
Minimally invasive percutaneous techniques, such as for example radio-frequency (RF) and microwave (MW) ablation of malignant tissue in the liver is a rapidly expanding research field and treatment tool for patients who are not candidates for surgical resection or liver transplant. In some cases, these minimally invasive percutaneous techniques act as a bridge to liver transplantation. Due to low complication rates and short recovery times, the indications for these minimally invasive techniques are increasing. These techniques, however, have a higher local recurrence rate than surgical resection mainly due to insufficient or inaccurate local ablation of cancerous cells.
MW energy-induced tissue heating by near field probes is a common thermal treatment of liver tumours. Application of MW for tumour ablation has multiple advantages over other techniques, including higher treatment temperatures and the ability to create larger uniformly shaped ablation zones in shorter time periods. However, the accurate placement of the ablation probe is critical in achieving the predicted treatment goal. The current standard uses computed tomography (CT) images for planning and two-dimensional ultrasound image guidance for intra-operative guidance of the ablation probe(s) into the target lesion. This approach suffers from several disadvantages such as: (1) 2D ultrasound imaging requires users (physicians) to mentally integrate a sequence of 2D images to form an impression of the anatomy and pathology, leading to variability in guidance during interventional procedures; (2) 2D ultrasound imaging does not permit the viewing of planes parallel to the skin; (3) liver deformation and motion artifact due to breathing reduces targeting accuracy; (4) the use of 2D ultrasound imaging for measurement of tumour volume needed for the treatment plan is variable and at times inaccurate and (5) the use of 2D ultrasound imaging makes it difficult to detect and track the needle delivering the thermal energy to the liver, which is crucial for accurate placement of the needle relative to the tumour.
The use a three-dimensional (3D) ultrasound imaging helps to overcome the above-noted disadvantages resulting in improved accuracy of ablation probe placement and improved ablation of the lesion. 3D ultrasound imaging also helps to show the features of liver masses and the hepatic vasculature more clearly, allowing guidance of the ablation probe to the target to be carried out more accurately and allowing more accurate monitoring of the ablation zone during the procedure and during follow up. As a result, 3D ultrasound imaging helps to increase the overall success rate and reliability of minimally invasive liver interventions. Thus, 3D ultrasound in combination with follow up CT images can help physicians to decide whether a repeat ablation is required.
The ability to increase the overall success rate of minimally invasive techniques for the treatment of liver cancer provides better treatment options for non-surgical candidates. It is them fore an object of the present invention at least to provide a novel mechanical tracking system to assist in medical imaging.